Reply on RC2

Abstract

The changes in soil properties and root traits caused by plant growth might have great effects on the process of soil detachment by overland flow. On this basis, two typical herbaceous plants, Bothriochloa ischcemum (Linn.). Keng (BI; fibrous root system) and Artemisia vestita Wall. ex Bess (AG; tap root system), from the Loess Plateau were studied for one year under six planted densities of 5 plants m−2, 10 plants m−2, 15 plants m−2, 20 plants m−2, 25 plants m−2, and 30 plants m−2 to determine how the soil detachment rate responds to soil properties and plant root traits. In total, 24 steel tanks were planted, and two plots were used as bare soil controls. Their soil detachment rates were tested under a constant overland flow (1.5 l s−1) on a 26.2 % slope. The results showed that the soil detachment rate under the six planted densities ranged from 0.034 kg m2 s−1 to 0.112 kg m2 s−1 for BI and was ranged from 0.053 m2 s−1 to 0.132 m2 s−1 for AG, which all greatly reduced soil detachment rate and were 68.17 % to 92.33 % and 69.20 % to 87.27 % less than that of the control. In general, BI was more effective in reducing the soil detachment rate than AG, achieving a mean soil detachment rate that was 23.75 % lower. With increasing plant density, the soil detachment rate decreased as a power function (R2 = 0.23, p < 0.01). The overland flow hydraulic characteristics, soil properties and root traits influenced by plant density were positively or negatively correlated with the soil detachment rate. Specifically, the soil detachment rate decreased with velocity, bulk density, root length density, and increased with shear stress and the Darcy–Weisbach friction factor as power or exponential functions (R2 ranged from 0.16 to 0.54, p < 0.01). On this basis, the soil detachment rate (Dr) can be satisfactorily estimated by the overland flow velocity (v), soil bulk density (BD) and root length density (RLD) as a power function (Dr = 5.636v0.118 × BD−19.917 × RLD−0.170; R2 = 0.58; NSE = 0.78; p < 0.01).